From 0a32ef9041670b3dfc02ace226b8975284567fdb Mon Sep 17 00:00:00 2001
From: Juan Ferrer Toribio <juan@verdnatura.es>
Date: Sun, 25 Dec 2022 14:28:42 +0100
Subject: [PATCH] refs #4550 Concurrency improved

---
 print-server.js | 74 ++++++++++++++++++++++++++-----------------------
 1 file changed, 39 insertions(+), 35 deletions(-)

diff --git a/print-server.js b/print-server.js
index 200b716..72c7726 100644
--- a/print-server.js
+++ b/print-server.js
@@ -18,6 +18,7 @@ class PrintServer {
         if (fs.existsSync(localConfFile))
             conf = Object.assign({}, conf, yml(localConfFile));
         this.conf = conf;
+        this.jobs = [];
 
         console.clear();
         const decoration = '△▽'.repeat(10);
@@ -33,7 +34,7 @@ class PrintServer {
         process.on('unhandledRejection', this.rejectionHandler);
 
         this.serverLog('log', 'Ready to print'.green);
-        setTimeout(() => this.poll());
+        await this.poll();
     }
     async stop() {
         this.serverLog('log', 'Bye ( ◕ ‿ ◕ )っ'.green);
@@ -102,8 +103,16 @@ class PrintServer {
             console.error(err);
     }
     async poll() {
-        const conf = this.conf;
         this.pollTimeout = null;
+        let delay = this.conf.refreshRate;
+        await this.getJobs();
+        if (this.dbDown) delay = this.conf.reconnectTimeout;
+        this.pollTimeout = setTimeout(() => this.poll(), delay);
+    }
+    async getJobs() {
+        if (this.polling) return;
+        this.polling = true;
+        const conf = this.conf;
 
         if (this.dbDown) {
             try {
@@ -121,37 +130,27 @@ class PrintServer {
 
         if (!this.dbDown) {
             try {
-                let jobs;
                 let nJobs = 0;
-                do {
-                    jobs = [];
-                    for (let i = 0; i < conf.concurrency; i++) {
-                        const jobId = await this.getJob();
-                        if (jobId) {
-                            const job = this.printJob(jobId);
-                            // XXX: Workaround for Promise.all() unhandledRejection
-                            // https://stackoverflow.com/questions/67789309/why-do-i-get-an-unhandled-promise-rejection-with-await-promise-all
-                            job.catch(() => {});
-                            jobs.push(job);
-                        }
-                        else
-                            break;
-                    }
-
-                    nJobs += jobs.length;
-                    await Promise.all(jobs);
-                } while (jobs.length);
-
+                while (this.jobs.length < conf.concurrency) {
+                    const jobId = await this.getJob();
+                    if (jobId) {
+                        nJobs++;
+                        this.jobs.push(jobId);
+                        const jobP = this.printJob(jobId);
+                        // XXX: Workaround for Promise unhandledRejection
+                        // https://stackoverflow.com/questions/67789309/why-do-i-get-an-unhandled-promise-rejection-with-await-promise-all
+                        jobP.catch(err => this.errorHandler(err));
+                    } else
+                        break;
+                }
                 if (nJobs > 0)
-                    this.serverLog('debug', `${nJobs} jobs printed`);
+                    this.serverLog('debug', `${nJobs} jobs buffered`);
             } catch (err) {
                 this.errorHandler(err);
             }
         }
 
-        let delay = this.conf.refreshRate;
-        if (this.dbDown) delay = this.conf.reconnectTimeout;
-        this.pollTimeout = setTimeout(() => this.poll(), delay);
+        this.polling = false;
     }
     async getJob() {
         let jobId;
@@ -281,17 +280,22 @@ class PrintServer {
             throw jobErr;
         } finally {
             conn.release();
+
+            if (!conf.keepFile) {
+                try {
+                    const shouldDelete = tmpFileCreated
+                        || (tmpFilePath && await fs.pathExists(tmpFilePath));
+                    if (shouldDelete) await fs.unlink(tmpFilePath);
+                } catch (err) {
+                    this.jobLog(jobId, 'error', err.message);
+                }
+            }
+    
+            const index = this.jobs.indexOf(jobId);
+            if (index !== -1) this.jobs.splice(index, 1);
+            setTimeout(() => this.getJobs());
         }
 
-        if (!conf.keepFile) {
-            try {
-                const shouldDelete = tmpFileCreated
-                    || (tmpFilePath && await fs.pathExists(tmpFilePath));
-                if (shouldDelete) await fs.unlink(tmpFilePath);
-            } catch (err) {
-                this.jobLog(jobId, 'error', err.message);
-            }
-        }
     }
     jobLog(jobId, realm, message) {
         this.log(`Job[${colors.yellow(jobId)}]`, realm, message);